It is known in the prior art that if a cover or similar is to be provided on a metal housing, it is made starting from a sheet, which is shaped into a box-shaped component. Rectangular/square cut-outs are made in the four corners of a rectangular standard flat sheet metal plate. The plate is then folded along the four side edges in order to form the four side walls. The corresponding end parts of the oppositely lying side walls are then welded together in order to form a corner region. These corner regions may be finished by means of a polishing machine.
U.S. Pat. No. 6,895,796 issued on May 24, 2005 to Markus Harmeter described an apparatus and method for trimming the work piece in such a forming process. More particularly the patent teaches the method of forming a corner region of a flat plate having side edges comprises the steps of folding down the side edges of the flat plate by a predetermined height from a plate in which the flat plate extends to form two intersecting side walls having free end faces and an excess projection in the corner region where the side walls intersect, placing the free end faces of the side walls on guide surfaces of bearing elements for the side walls, placing the excess projection between two cutting elements having cutting edges in alignment with the guide surfaces of the bearing elements, and separating the excess projection by displacing one of the cutting elements against the other cutting element. More particularly, Harmenter teaches guide surfaces that are perpendicular to the formed corner side wall. Accordingly the cutting edges aligned with the guide surfaces move precisely in a direction that is parallel to plane that is perpendicular to each side wall.
A problem with the prior art method and apparatus described therein is that the process of separation of the excess projection results in burring of the free end faces of the side walls. In addition, the side wall cut often results in an edge that does not have all points within a single plane much less a plane that is perpendicular to the respective side walls of the formed corner. FIGS. 7 and 8 herein illustrate examples of imprecision in the formation of trimmed side wall of a corner bounded on three sides from a flat sheet material. FIG. 6 illustrates a precisely formed side wall of a corner bounded on three sides from a flat sheet material. Accordingly, it is therefore seen that there exists a need in the art to overcome these deficiencies and limitations.
The present invention includes the method as well as apparatus that is free standing and independent of another forming apparatus as well the method and apparatus that is physically integrated with known preprocessing apparatus such as the prior art apparatus described in the Harmenter patent as well as work pieces formed by other means such as an edge-folding press. To best illustrate possible cooperation with the prior art apparatus this description will refer specifically to the prior art apparatus described in the Harmenter patent including some of the specific drawings shown in the Harmenter patent to describe an embodiment of the present invention that in addition to trimming the formed corner also forms the corner.
FIGS. 26 and 27 of Harmenter provide a detailed illustration of the cutting device 113 of the prior art corner-shaping device 4. On the cutting plate 14, the stationary cutting element 157 is detachably secured by a bottom face 186 extending parallel with the cutting plate 14, e.g. at a distance 187 from the cutting plate 14 by means of a spacing batten 185. Accordingly, the cutting element 157 acts as a cutting edge 163 projecting beyond the spacing batten 185 in the direction of the displaceable cutting element 158, formed by the bottom face 186 and an end face 188 extending perpendicular to the cutting plate 14. The distance 187 corresponds more or less to a thickness 189 of the displaceable cutting element 158, which is guided on the cutting plate 14 in a linear displacement driven by the drive system 160, e.g. a pressurized cylinder, and forms the cutting edge 164 with the front end face 168 and a top face 190. In this prior art method and apparatus the displaceable cutting element 158 advances toward the formed corner sides in a direction that is precisely perpendicular as shown in FIG. 26.
On an end face 188, the cutting element 157 is provided with a V-shaped cut-away 191 adapted to the corner region 10 of the component 2 to be cut, directed towards the cutting element 158. The displaceable cutting element 158, on the other hand, has a nose-shaped projection 192 opposite the stationary cutting element 157 which is of the same shape as the cut-away 191 and forms the front end face 168. Clearly, the cut-away 191 has an internally rounded contour in the corner region 10 adapted to the component 2 and the projection 192 has a matching externally rounded contour.
When shaping the corners, in order to trim and remove the projection 194 standing out from the resultant end faces 193 of the side walls 8 in the corner region, the component, with its opening directed towards the displaceable cutting element 158, is manually positioned with the end faces 193 flat against the latter and the corner region 10 in the cut-away 191. When the cutting element 158 is displaced by the drive system 160 towards the stationary cutting element 158, a cut is made along the end faces 193 of the component 2 in the corner region 10 to remove the projection 194.
When the component 2 is placed on the base plate 195 in readiness for the cutting process, an infeed is activated by the drive 196 of the tool holder 198 in the direction of arrow 200, until the displaceable cutting element 158 bears on the end faces 193 of the side walls 8 with a bottom face 201. The bottom face 201 of the displaceable cutting element 158 is aligned flush with a top face 202 of the stationary cutting element 157. The cutting position has therefore been reached and the displaceable cutting element 158 is displaced via the drive system 160 in the direction of arrow 203 and hence towards the stationary cutting element 157 until the side wall 8 of the component 2 bears on the end face 188 of the stationary cutting element 157. As displacement continues in the direction of arrow 203, the projection 194 produced when shaping the corner is trimmed exactly flush with the end faces 193 due to the co-operation of the cutting edges 163, 164 with the cutting elements 157, 158. After the cutting process, the tool holder 198 is displaced by the drive 196 in the direction opposite arrow 200 into an open position at a distance from the base plate 195, after which the component 2 can be removed from the cutting device 113.
As may also be seen from FIGS. 26 and 27 described above in relation to the cutting device 113, as the projection 194 is trimmed, an exactly flush path to the end faces 193 of the side walls 8 is achieved due to the fact that bearing elements 205 forming guide surfaces 204 are provided, either on the cutting plate 14 or separately from it or from the machinery 101, on which the component is laid by its end faces 193 of the side walls 8 and in its corner region 10 with the projection 194 projecting between the cutting elements 157, 158. The cutting elements 157, 158 are arranged so that the cutting edge 163 of the cutting element 157 and the cutting edge 164 of the cutting element 158 are disposed running in the guide surface 204 formed by the bearing elements 205. As the cutting process proceeds, i.e. by displacing the displaceable cutting element 158 relative to the stationary cutting element 157, the projection 194 standing out by a height 206 of the side walls 8 is trimmed exactly flush in order to achieve the height 206 of the side walls 8, even in the corner region 10, without any discrepancy.
As may also be seen from the broken lines of FIG. 27, another option is to provide the displaceable cutting element 158 with bearing elements 205 on it in the form of projections, so that the component 2 is supported by its side walls 8 in the immediate vicinity of the corner region 10 to be cut.
As may also be seen from FIG. 25, a height 212 of the tool 16 or the peripheral shaping surfaces 36 is greater than the height 206 of the side walls 8 of the component 2. In any event, the height 212 of the shaping surfaces 36 amounts to a measurement corresponding to the height 206 of the side walls 8 plus an anticipated height 213 of the projection 194. As a result, this ensures that when shaping the corner region 10, the projection 194, once formed by the roll, will always lie flat in the region of the shaping surfaces 36 and will not be drawn in against the bottom face of the tool 16 under any circumstances, which would result in jamming, making it more difficult to remove the component 2 once the corner region 10 had been formed.